Add better progress information output for long operation.

Checking sha256sum and downloading file can be pretty long.
Let's print few information to the user.

kiwix-build.py

@@ -15,6 +15,7 @@ from utils import (
     remove_duplicates,
     add_execution_right,
     get_sha256,
+    print_status,
     StopBuild,
     SkipCommand,
     Defaultdict,
@@ -440,11 +441,22 @@ class BuildEnv:
             context = None
         batch_size = 1024 * 8
         extra_args = {'context':context} if sys.version_info >= (3, 4, 3) else {}
+        progress_chars = "/-\|"
         with urllib.request.urlopen(file_url, **extra_args) as resource, open(file_path, 'wb') as file:
+            tsize = resource.getheader('Content-Length', None)
+            if tsize is not None:
+                tsize = int(tsize)
+            current = 0
             while True:
                 batch = resource.read(batch_size)
                 if not batch:
                     break
+                if tsize:
+                    current += batch_size
+                    print_status("{:.2%}".format(current/tsize))
+                else:
+                    print_status(progress_chars[current])
+                    current = (current+1)%4
                 file.write(batch)
 
         if not what.sha256:

utils.py

@@ -27,11 +27,23 @@ def remove_duplicates(iterable, key_function=None):
 
 
 def get_sha256(path):
+    progress_chars = "/-\|"
+    current = 0
+    batch_size = 1024 * 8
     sha256 = hashlib.sha256()
     with open(path, 'br') as f:
-        sha256.update(f.read())
+        while True:
+            batch = f.read(batch_size)
+            if not batch:
+                break
+            sha256.update(batch)
+            print_status(progress_chars[current])
+            current = (current+1)%4
     return sha256.hexdigest()
 
+def print_status(status):
+    text = "{}\033[{}D".format(status, len(status))
+    print(text, end="")
 
 def add_execution_right(file_path):
     current_permissions = stat.S_IMODE(os.lstat(file_path).st_mode)